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The Boo

Phase 1, pg. 2

12/10/05 Imagine my surprise when I show up at the airport today to get some hours burned off and I find the taxiway is gone!  They're building a row of hangars to the north of mine and in the process decided to rebuild the taxiway.  It would have been nice if they told us.  Everything is conspiring against me to get these hours flown off.

Oh well, at least I could do my oil change.  Last weekend I drained all the oil but didn't have the correct oil filter so I waited till this weekend to add the oil back and change the filter.

I purchase a oil filter cutter.  Not cheap at $90 but it does a great job.  Nothing in the filter, yehoo.

Here the set of plastic tie-downs I got from McMaster-Carr

Please say a prayer for my dad, he had a heart attack yesterday.  They placed two stents in two arteries and he seems to be doing much better.  That is until I called him tonight and he said that he was running a fever and had a sore throat.  A cold or pneumonia is not a good thing right now.  Hope you make a full recovery pops.  I'm getting anxious to get you in the air!

12/19/05 A little update on Pops.  He's at home and expected to make a full recovery.  I'll be heading home on Wednesday to visit and share Christmas with the family.  Can't wait to go and see the snow and feel the biting Michigan winter :)

No flying this past weekend (again).  We had our annual Skechers Christmas party on Friday night and well lets just say everyone had a very merry time.  Sunday was spent at TOA helping Skylor get his engine hung.  Seems like every time an engine gets hung around here in SoCal about 40 people show up and have a great time.  The SoCal gang put on an awesome mini-air show and the BBQ was excellent.  When is the next BBQ?  Who's next with the engine hanging???

12/7/05 Weather cooperated this weekend and the gods were smiling so I got another two hours burned off today.  Took my video camera up to get a small video but ran out of battery juice after a minute of video.  Oh well, it's still sort of neat.

The video

12/8/05 Flew another two hours today as well.  She's flying real nice.  Today it seemed like the engine was running extra smooth.  Although I still have high CHTs.  Now they are running in the 430-440 range.  Pmags are supposed to show up in two weeks.  I would like to burn off 35 hours of flying then install them so I don't have to put the plane back into phase 1.  As of now I have about 23 hours flown off.


Today, Bill Marvel and I went ahead with the testing of the pressure differential between the airspace above the cylinders and the area below the cylinders as he recommended.  Bill had an article called "Engine Cooling Problems - Diagnosis For Homebuilt Airplanes" by JIMMY TUBBS.  It's a excellent and well written piece.  Unfortunately I do not have an electronic copy of it and the fax thermo paper copy Bill has is so light as to be transparent and would not do well in the copy or fax machine, so I will provide you with some of the details of the article in this thread along with the matching pictures I took today to give you the visual...

Quoted from JIMMY TUBBS article:

"The technique we use to evaluate the health of a cooling system is to install a water manometer or an extra airspeed indicator in the cockpit in full view of the pilot or assistant.  The airspeed indicator is connected to small instrument type hoses that are routed through the firewall with one hose going to the top of the engine and one below the engine.  The ends of the hoses are blocked with a plug (bolt in our case), and holes are drilled randomly around the hose in the last inch from the plugged end.  The hoses should be routed so that they are clear of the exhaust system, and should be securely fastened along the routing.  We normally attach the upper hose to the lifting eye on top of the engine.  The bottom hose should be in the area of the sump, and should not be too near the exit to the cowl, since funneling of the air will skew the readings. [...]  If an airspeed indicator is used (as was the case in our test), attach the hose from above the engine to the pitot side and the lower hose the the static side. 


Airspeed indicator and location of top hose attached to the engine lifting eye.  Pictures were taken before we secured the hoses.  You can see the hose end with plug and holes drilled.

Top hose was run through the spark plug hole above Cyl #3.

Lower hose laid next to the sump on the right side.

Hoses were then run through two holes I had available through the firewall and into the cabin.  One thing you might want to do when building is to allow two holes through the firewall which you plug with stainless caps found at Home Depot Airparts.

Here's the man I need to thank for his time and effort to help me, Mr. Bill Marvel.  Thank you!  If you haven't seen some his prior work, do a Google search, you'll be amazed.

When the airplane is ready, flight testing is conducted by flying the airplane in climb and cruise while recording airspeed, power setting, CHT , oil temp, OAT, mixture and instrumentation readings.  The instrumentation readings will be in miles per hour or knots if using the airspeed indicator, or in inches of water if using a manometer.  The method of converting airspeed readings to inches of water is given in Table 1. 

30 26.1 .44 .016
40 34.8 .79 .028
50 43.5 1.23 .044
60 52.2 1.77 .064
70 60.9 2.41 .087
80 69.6 3.15 .114
90 78.3  3.99 .144
100 87.0 4.92 .178
110 95.7 5.95 .215
120 104.3 7.09 .2558

                         Table 1.

Obviously, cooling airflow and pressure drop will be higher at cruise than during climb.  However, both values are necessary to verify a good cooling system for most airplanes.  The climb portion of the test should be conducted at the speed for maximum climb rate and at faster climb speeds that represent the more normal climb attitude.  Of course, the climb cooling tests are conducted at rich mixture settings unless the altitude requires leaner mixtures to smooth the engine.

The cruise tests should be accomplished at low through high cruise power settings using both rich and lean mixtures.  It is helpful if cylinder head temperature (all cylinders if possible), oil temperature and OAT can be monitored and recorded during the testing, but this is not absolutely necessary to make a good evaluation of the cooling system.


Teledyne Continental has not published the pressure drops they desire for their engines, but the Lycoming Engine Installation Manual does specify that the O-320 engine requires 5 - 1/2 inches of water while the O-360 engine should have 6 - 1/2 inches pressure drop for good cooling.  6 - 1/2 inches of water is only .2346 pounds per square inch, so the drop does not represent a big pressure change.  TCM engines should be comparable.


If the pressure drop is above 4 - 1/2 inches of water in climb, then a cooling problem is probably engine-related and not due to the cowling, baffling or cooling system design.  However, if the readings are at the 1 to 3 inches of water level during climb (or lower), then adjustments should be made.  The areas that need to be looked at are: 1. Inner cylinder baffling  2. Gaps in engine baffling and in the seal to upper cowl  3. Insufficient, poorly designed or poorly constructed air inlets  4. Insufficient, poorly designed or poorly constructed air outlets.


The best baffle seal material is made with silicone rubber (red).  This material holds its shape much better, and is more heat resistant than the older cowl seal material.  However, do not use the commercially available material that has an aluminum mesh between the layers.  This can cut right through your cowl.

After sheet metal repairs are made to close obvious gaps, the next tool is RTV High Temperature Silicone Sealant. [...]  There is a persistent rumor that closing one square inch of gap will raise the pressure drop one inch of water.  This has not been confirmed, and would only be an average expectation.

Changing the design of the cowling  should be the last item to evaluate.  This is done after the easy stuff is tried and flight tests conducted to verify that the cooling problems persist.  Generally, the problems are not caused by the air inlet holes unless the holes are extremely small.  The exit to the bottom cowl, however, may be the culprit, and is often overlooked in the quest to solve cooling problems.  As the engine is cooled, the cooling air heats up and expands, so the exit needs more area than the inlet and its location in a low pressure area of the airframe is essential."

Ok, so that's the jist of the article.  It's a good read, I wish I could spend all night typing it in but, hey, I'm lazy tonight so you only get part of it, but I've typed in the pertinent parts for this test.

Our Results???

Well lets first get on with what most of you have been saying publicly and noted in this article, which is very important.  Make sure your baffles are in excellent shape.  My baffles are in very good shape.  I have used RTV in every crack and crevice.  I even use the Silicone baffle material mentioned in the article, with no gaps.  The inter cylinder baffles are made at the factory and were in place when I got the engine and as far as I can see, they are in excellent condition.  And my cylinders have no excess flashing commonly found. 

So that leaves us with the hypothesis that the exit area might not be large enough, causing the high cylinder head temperatures I've been experiencing, hence this test.  If the test proves that we were not getting enough outflow, differential pressures, then I would be faced with the next step which is to add louvers.  In fact I have a pair on order from Vans now, just in case.

Well the results were less than stunning.  I expected to see the airspeed indicator show less than what was required, but I was proven wrong.  At 23 squared and 5000 feet we were showing about 110 mph on the airspeed indicator; about a 6 inch drop and to make matters even stranger we never saw the CHT's get above 400 during cruise, and to make it even stranger I never saw the oil temp above 176, as it usually hovers around 190 - 195.  Now some of this could be contributed to the fact that today was the coolest day that I've ever flown since first flight at about 5 C, much less than the 20-25 C that we've been seeing here lately.  I won't know what the effect of OAT has until I fly during a relatively hot day as a comparison.  But, it is safe to assume after this test that there is adequate differential pressure to provide ample cooling with the existing cowl inlet/exit as it stands today, provided the OAT is 5 C.

During the flight Bill asked me if I've done any full power runs, FULL POWER RUNS.  And to the best of my recollection I had not, simply due to the fact that immediately after takeoff my temps were already into the 400's and I felt it was better to pull the power and not run WOT.  So as a test we dove to 3500 ft and ran with the prop running 2650 and power at max.  To my amazement the CHT's didn't climb past 411.   So perhaps one could assume that the engine is not quite run-in as it should be. 

Could it be that as far as oil consumption goes the engine is broken in but that there is still considerable heat being generated by the cerminil cylinders?  Perhaps.  I did speak to Penn Yan Aero folks and they did mention that it might take as much as 20-30 hours to break in these cylinders.  Well I need to do more research on the cerminil cylinders.  And I need to run WOT for the foreseeable future, down low, until the CHTs come more into line as I expect they will.

As for hard numbers, Bill has them on his notepad and I will try to get them in the near future.  This has been a very enlightening experience, one in which my theories were shot down.  But it was a great learning experience.  Experimental airplanes RULE!  Do the work yourself and you shall be rewarded.

2/29/06 Well I've been receiving a lot of emails asking me WTF? how come you don't update your website!  Well it's like this:  It was a dark and stormy night, and I decided that going for a jog would be beneficial.  I've been going to the gym on a regular basis lately and I round it out with a good 3 mile jog three times per week.  But that night I made the mistake of jogging where there were no street lights and I got mugged.  NOT, actually I fell into a hole in the concrete and severely sprained my ankle (again).  So three weeks with no flying while I rehab.  Speaking of rehab, the witch running my rehab is out to kill me, I swear it.  But it must be working.  I'm now able to fly again.  So hopefully this weekend I'll get some air under my lederhosen.  BTW, still waiting for the P-mags :)  Hopefully next week I'll get them.  I've promised to do a concise installation picture review.
3/5/06 Pulled the AP head unit for it's Vertical Guidance upgrade ($500).  Also got word tonight that the GRT XM weather will be shipping next week.  WooHoo.  Been playing around with the GRT checklist option as well.  I have it about 95% complete.  If you want to see what I have so far, here it is.
3/6/06 Alriiiight.  Just got notified that the GRT XM weather will be here in two days.  WooHooo.
3/11/06 Autopilot ready to be reinstalled after the upgrade.

Here's the GRT XM weather receiver, antenna and wiring harness.  It's really small, fits in my hand and is very light.  No idea what the USB and RF Out are for.  Nothing in the documentation either.

Bought some parts for the upcoming Fuel Pickup SB too, cork gaskets which will replace the rubber gaskets if they get torn up in the removal process and some new fuel pickups.  The ones I have are the aluminum tubes with slices in it, like someone took a hacksaw to them.

I knew this was going to happen, a run on Proseal.  Here's Van's idea of an SB.  They tell you you have to do it before next flight but they run out of proseal.  Guess I saw that one coming.

Bought a 256MB compact flash card and a PCMCIA CF adaptor for the GRT terrain feature.

Time to yank the #2 display unit.  This unit will receive the CF PCMCIA card as it's the #2 unit which I use for NAV.  Do you think I was an early adopter of GRT products?  Check out the serial number - #39.

Removed all the screws on the casing and here's the guts.  Not very good pictures but there's a slot and an eject button in there for the CF PCMCIA card.  Nicely done.  Put it all back together but I have to finish the wiring on this DU, the XM weather wiring will go to this unit as well.

4/30/06 Got another 2.9 hours flown today on the new p-mags.  Flew perfectly, no issues at all with the new installation.  Did see CHT at 430 on #4 cylinder in the climb with full mixture.  Running LOP all day burning 6.3 gals/hr, 2200 RPM and 21" MAP sees CHT all between 350-360 except #4 which is 20 degrees hotter.  In the climb I saw oil temps reach 200 but in cruise they were down in the high 170's.  Not enough information to go on yet.  I'll begin to do some performance runs next weekend and data-log the information.  I was just happy to fly today even though the visibility was crapola below 3000.

I can run LOP quite easily but I have to mess with the injectors a bit to get all four cylinders dead nuts; three of them are pretty much the same but the #3 injector is running a bit lean.  May swap it out with the richest injector. 

Just happy to be flying.  Like my new 30g's?  They're a hell of a lot better than my old David Clarks from 1991.

5/7/06 Another two hours on the books.  So close I can taste it.  We've had about a month of the crappiest weather here in SoCal.  Yesterday we waited until 1:30pm then decided that we had other crap we could do.  Headed over to Van Nuys and picked up a copy of One Six Right.  Awesome movie.

I'm on vacation for the next two weekends so no flying for some time.

Running LOP I get two cylinders at 40 LOP and one at 50 LOP and the last one at 60 LOP.  It varies a few degrees here and there but pretty consistent.  CHT runs between 350 and 400 on #4.  I blocked off 2/3rds of the heater air vent but that had no effect. 

While at 8000 ft I moved the mixture from LOP to 50 degrees ROP and firewalled the throttle and moved the prop to 2400.  Highest CHT was just under 440.  Still too hot but 20 degrees less than with the LASAR and it was good and hot today too. 

I starting to feel that some louvers may be the solution.  I'll let you know in a few weeks.

6/4/06 After fixing the p-mags and finally getting to the root cause of my high CHT temps, I finally got my bird home.  Mike was kind enough to fly me over to CNO.  David came along for the nice flight over.  Pulled 447RV out of it's nest and flew home to Compton (KCPM).  Wow, now I can every day if I want as it's less than 15 minutes from the front door. 

The runway is just a few short feet away.

Yeah, the outside may need paint but the inside is great, and best of all, it's all mine.

Phase 1 is officially OVER!


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Last updated: 07/06/05.